Threaded fastening devices known as Tee-nuts are widely used in the furniture and other industries for securing components of for example furniture together. Such Tee-nuts are formed of sheet metal, and incorporate a threaded sleeve or barrel, and an integral face flange, and spikes, which are embedded in the workpiece around a pre-drilled hole. They are used, for example, in the construction of beds, for securing legs to various furniture items.
Various forms of apparatus have been devised for the power-operated setting of such Tee-nuts at a high rate of speed. One example of such a Tee-nut setting apparatus is shown in U.S. Pat. No. 3,460,217.
The apparatus disclosed in that patent has operated satisfactorily for many years. In that apparatus, the workpiece was first of all placed on a lower working surface. Tee-nuts were fed from a hopper down a curved ramp, to a power-operated setting plunger located above the workpiece. The Tee-nut was held in registration with the bottom of the plunger, and when the plunger was operated downwardly the Tee-nut was released, and the plunger struck the Tee-nut forcing it downwardly into a hole in the workpiece.
One problem in the design of such earlier machines was that they required the use of a hopper, and a relatively expensive feed mechanism, for feeding the loose Tee-nuts. These requirements added to the complexity and hence the expense of such earlier apparatus. These factors had, in turn, limited the scope of the sales of such machines. In practice, they were economical only for relatively large scale manufacturing facilities.
A further proposal is shown in U.S. Pat. No. 4,821,940, granted to Allan C. Rotherham entitled Tee-nut Insertion Machine.
In this machine, a hopper and feed mechanism generally similar to that shown in earlier Tee-nut setting machines, was used. However, in this machine, the Tee-nuts were fed to a feed mechanism from which they were delivered one at a time to a plunger. The plunger in this case operated with an upward insertion stroke, so that the Tee-nut was forced upwardly into the workpiece.
Above the workpiece, a stationary anvil or support was located against which the workpiece was held, while the Tee-nut was forced upwardly. In this device, however, the Tee-nuts were simply placed loose in the hopper as in the earlier devices, and as a result, it was necessary to provide for a two position delivery system for delivering the Tee-nuts to the plunger.
The Tee-nuts were thus delivered to a preliminary delivery location, at which point they stopped. The endmost tee-nut was then moved over a step by a piston, one at a time, from the preliminary location, to the so-called extended location, in which position it was then held ready for insertion by the plunger.
Clearly, if a feed mechanism could be designed at a much lower cost and, in particular, without the use of an expensive and complex hopper and feed mechanism, and without the hopper and two-step feed mechanism of U.S. Pat. No. 4,821,940 then the sales of such a machine could be made on a much larger scale, to a much greater range of customers.
The setting machine may operate on the method of upward insertion of Tee-nuts, into a work-piece from below the work-piece, or by moving each Tee-nut downwardly, and in either case the feed mechanism will produce significant advantages over earlier systems.
Preferably also, the invention will provide for a new and unique package of such Tee-nuts arranged in a strip, for easy handling, and positioning in such a feed apparatus.